Time-resolved three-directional three-dimensional (3D) phase-contrast MRI, often referred to as “4D Flow MRI” or simply “4D Flow,” is a powerful tool for the noninvasive measurement of blood flow in the cardiovascular system. The 4D Flow technique obtains anatomical and three-directional velocity information, for each voxel within a 3D-volume and at each measured time point of the cardiac cycle.
4D Flow has traditionally been used for imaging of the cardiac structures such as the aorta, cranial arteries, carotid arteries, etc. Recently, 4D Flow applications have been extended for the measurements of the portal venous flow in the liver for patients with portal hypertension for surgeries such as transvenous intrahepatic portosystemic surgery. The current method for this liver application, however, is not effective as the technique excites a large field of view with low resolution that covers regions that are not of interest, thus can extend the scan time. Furthermore, the use of traditional 90-180 cross section navigator is cumbersome for this application and can interfere with the signal of the imaging volume.